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Modem Wiring Pinouts
C - 2
C.3 Modem Wiring
C.3.1 DSR (Data Signal Ready) versus CD (Carrier Detect)
By default, most modems assert CD only during a valid connection. In this
case the modemÕs CD pin may be wired to the ServerÕs DSR pin. Alternately,
many modems can be conÞgured such that DSR acts like CD. In this case, the
modemÕs DSR pin may be wired to the ServerÕs DSR pin.
C.3.2 DTR (Data Terminal Ready)
The MSS normally asserts DTR. When modem control is enabled on the MSS,
the server will de-assert DTR for three seconds each time the port is logged
out and each time a user disconnects from a modem service. The modem
must be conÞgured to hang up and recycle when DTR is de-asserted. If the
modem is not conÞgured in this way, sessions may not be properly
disconnected.